Folic acid or folate is a B vitamin required in the body for the healthy production of new cells. It has recently received attention in the nutritional world due to the publication of a meta-analysis in the Lancet (which included a study carried out in China) linking folic acid supplementation to a lower incidence of stroke, especially in countries where food is not fortified with folic acid.

This effect is thought to be due to a reduction in internal levels of homocysteine. Homocysteine is an amino acid, which is naturally present in the body, however high circulating levels are thought to be associated with a marked increase in risk of cardiovascular disease.

Another significant role of folic acid is in the prevention of neural tube defects (NTDs), such as spina bifida, in unborn babies. NTDs have been observed in higher frequency in northern China where fruit and vegetables (and so folate) are less available versus the south. Worldwide, women planning to conceive are advised to take a supplement to ensure a daily intake of 600 micrograms of folic acid, and continue with this until the 12th week of pregnancy. Unfortunately, this advice often fails to reach those most in need of it, and additionally many pregnancies are unplanned. Consequently countries including the US, Canada and Chile have introduced mandatory fortification programs. This has yet to be implemented in China.

Since 1998 the USA has fortified a number of staple grain products including bread, pasta and rice. This has reportedly resulted in a 25 percent fall in the number of babies born with NTDs. Additionally incidence of stroke is now 3-5 times lower compared to China. In the UK a number of products such as breakfast cereal and some margarines are voluntarily fortified. More recently the issue of mandatory fortification has been debated for foods such as flour or bread, and this is likely to be implemented very soon. Fortification programs are subject to some controversy due to fears of folic acid masking B12 deficiency, which can lead to neurological problems, however this is only likely to occur at high levels of fortification.

For those not planning to conceive, it is quite possible to meet the daily recommended amount of 400 micrograms of folic acid through diet alone, although as it is a water soluble vitamin and cannot be stored it is required daily. Food sources are abundant in China. Dark green and leafy vegetables such as spinach, broccoli and any of the leafy greens are excellent sources, as are asparagus and lettuce. Beans, peas and pulses such as chickpeas and broad beans are also rich in folic acid. Citrus fruits like oranges and grapefruit, and their juices contain good amounts, as do melons and strawberries. Peanuts and sunflower seeds are a good choice. For a folate packed salad, combine a cup of cooked beans (lima, pinto, adzuki etc), with blanched asparagus and de-pithed orange segments. Sprinkle over some toasted sunflower seeds and coriander leaves and dress with lemon juice and olive oil.

This nutrition-related column is written by Nina Lenton, a qualified dietitian living in Beijing and working at Bayley and Jackson Medical Center. Contact her at nina.lenton@bjhealthcare.com.

(China Daily 06/20/2007 page14)